This invention relates to the generation of X-rays and, more particularly, to an improved X-ray source and to a method for fabricating such a source.
X-ray generators are utilized in a variety of applications of practical importance. One significant area in which such sources are employed is the field of X-ray lithography. An illustrative X-ray lithographic system utilized to make structures such as very-large-scale-integrated (VLSI) semiconductor devices is described in an article by M. M. Lepselter, "Scaling the Micron Barrier With X-Rays," Technical Digest 1980 IEDM, page 42. An advantageous water-cooled X-ray source for inclusion in such a system is specified by J. R. Maldonado, M. E. Poulsen, T. E. Saunders, F. Vratny and A. Zacharias in "X-Ray Lithography Source Using a Stationary Solid Pd Target," J. Vac. Sci. Technol., Vol. 16, page 1942 (1979). Such a source is also described in U.S. Pat. No. 4,258,262.
Continuing efforts have been directed by workers in the X-ray field at trying to improve the palladium target described in the aforementioned references. In particular, these efforts have been concerned with trying to devise an especially rugged high-power palladium target characterized by excellent stability, long lifetime and low maintenance. It was recognized that an X-ray source including such a target could be an important basis for realizing a rugged production-type X-ray lithographic system exhibiting advantageous characteristics.